Abstract
In this article, we discuss the synthesis, characterization, and reactivity of a neutral dicobalt complex, [Co (2) (PMe (3) ) (2) ] (0) , supported by a highly reduced, redox-active macrocyclic ligand. The reducing equivalents stored within the ligand framework proved capable of activating a wide scope of small molecule substrates. The addition of a weak acid, lutidinium triflate, led to the clean formation of a bridging hydride that was found to undergo fluxional geometric changes in solution, while exposure of [Co (2) (PMe (3) ) (2) ] (0) to H(2) resulted in a rare example of net binuclear oxidative addition to give two bridging hydrides. The addition of diphenylacetylene to [Co (2) (PMe (3) ) (2) ] (0) gave an unusual metallacyclobutane configuration for the coordinated alkyne, a geometry that was mirrored by the product obtained on activation of CO(2) by [Co (2) (PMe (3) ) (2) ] (0) . Dinitrogen was not observed to bind to [Co (2) (PMe (3) ) (2) ] (0) , but the use of catalytic quantities of [Co (2) (PMe (3) ) (2) ] (0) in mixtures of KC(8) and Me(3)SiCl under 1 atm of N(2) yielded N(SiMe(3))(3), which was quantified by conversion into NH(4)Cl. A screen of related dicobalt complexes revealed a dependence on the identity of the pre-catalyst, with yields of fixed nitrogen ranging up to 50(6) %.